Only clarify that 10 years Insurance only covers structural damages or induced by structural failures.
The other gurantees that spanish law provides are:
- 1 year for finish materials (tiles, painting,...)
- 3 years for installantions or damages induced by them.( Drainage included)
The structural guarantee is compulsory be covered by insurer. The other two can be covered by insurer or directly by the developer.
As you have said, the 10 years insurance is compulsory for sell a building made after May 2000. If it is ten years old you can sell it without insurance.
Also it is only for new building and integral reform buildings. If you make alterations at home the only valid guarantee is what you have agreed with buider, but legally one year for everything and two years for materials who has those guarantee.
Always demand a correct bill or will never can claim.